The present invention relates generally to safety equipment, and more particularly to anchors and methods associated therewith adapted to secure rock quarry workers when working near the edge of a quarry floor or deck.
Rock is removed from a quarry using well-known blasting methods, one of which includes removing rock from the face of a rock shelf to depths in the neighborhood of 50-60 feet. To prepare the edge portion of a rock shelf for blasting, vertically extending charge holes or "boreholes" are drilled into the floor or deck of the shelf, explosive charges are placed into the holes, and the explosives detonated for removal of the face or edge portion of the shelf. For these and other reasons associated with rock blasting, workers are sometimes required to work relatively close to the edge of the shelf.
Various laws, regulations, ordinances and the like, including those of the U.S. Department of Labor-- Mine Safety and Health Administration, require that workers be anchored to a stationary object whenever they may come within a certain distance, e.g., within 5 feet, of the edge of the quarry floor, so as to hold the worker if he falls off the edge of the shelf, thus preventing the worker from falling to the next lower shelf and often to the worker's death. For this reason, such workers are typically equipped with a safety belt or other harness arrangement that fits snugly around the waist area of the worker's body, and a tether line or safety strap, typically 10-15 feet in length, that hooks between the worker's safety belt and the stationary object the worker is anchoring to.
It has been common practice for a worker in this situation to anchor himself to a vehicle or heavy piece of machinery that is located nearby on the quarry shelf. For example, workers will often anchor themselves to a truck or a mobile drilling rig. However, such vehicles or machinery may not be immediately available in the area that the worker desires to go, and the worker must move the vehicle or machinery to the desired area before he can safely proceed into that area. Unfortunately workers do not always take the time to move a vehicle or machinery to a location for tethering to.
Prior techniques for anchoring to the quarry shelf have also included drilling a relatively shallow hole in the rock, e.g., 3-4 feet, and inserting a steel anchoring post into the hole. In this instance, the steel post is sized to rest on the bottom of the hole and extend to a height above the quarry floor, the upper end of the post being provided with a hook arrangement for connecting with the safety strap.
Of recent times, the Federal Mine Safety and Health Administration has discouraged the practice of workers anchoring to vehicles, mobile drilling rigs, and like equipment, because if such equipment falls from the shelf, as it does upon occasion, a tethered worker will be pulled over the edge with the machinery. This has resulted in increased use of the shallow-holes/steel post anchoring arrangement. Unfortunately, such posts are not easily portable as they are relatively heavy, and such an arrangement requires drilling holes in the rock in addition to the charge holes that are already drilled or to be drilled in the rock, resulting in additional time and expense associated with quarry work.
Thus, it is desirable to provide a lightweight, portable anchor that is suitable for use in a quarry, to enable the worker to quickly and easily carry the anchor to a desired location as he does his safety harness, and to easily move the anchor from place to place as the need arises for increased ease of worker mobility on the cliff. It is further desirable to provide such a portable, lightweight anchor that is suitable for use on a quarry shelf without the need to drill additional holes in the rock.